Imageable seamed belts having polyvinylbutyral and isocyanate outer layer

ABSTRACT

A seamed flexible belt with interlocking seam members having an outer layer including a polyvinylbutyral and an isocyanate, or a polyurethane from the reaction of polyvinylbutyral and an isocyanate, for use in the xerographic, contact electrostatic, digital and other like machines.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 09/886,841; filed Jun. 20,2001 U.S. Pat. No. 6,558,767.

Attention is directed to U.S. Pat. No. 6,318,223 filed Jan. 28, 2000,entitled “Process and Apparatus for Producing an Endless Seamed Belt;”U.S. Pat. No. 6,358,347, filed Dec. 22, 1999, entitled, “ContinuousProcess for Manufacturing Imageable Seamed Belts for Printers;” U.S.Pat. No. 6,316,070, filed May 28, 1998, entitled, “Unsaturated CarbonateAdhesives for Component Seams;” U.S. Pat. No. 6,379,486, filed Jul. 13,2000, entitled, “Polyimide Adhesive For Polyimide Component InterlockingSeams;” U.S. patent application Ser. No. 09/615,426 (D/99598Q), filedJul. 13, 2000, pending entitled, “Process For Seaming Interlocking SeamsOf Polyimide Component Using Polyimide Adhesive”; U.S. Pat. No.6,327,454, filed Sep. 13, 2000, entitled, “Imageable Seamed Belts HavingFluoropolymer Adhesive Between Interlocking Seaming Members;” U.S. Pat.No. 6,387,465, filed Sep. 13, 2000, entitled, “Imageable Seamed BeltsHaving Fluoropolymer Overcoat;” U.S. Pat. No. 6,527,105 filed Apr. 11,2001, entitled, “Imageable Seamed Belts Having Hot Melt Processable,Thermosetting Resin and Conductive Carbon Filler Adhesive BetweenInterlocking Seaming Members;” U.S. patent application Ser. No.9/833,965 (D/A0895Q), filed Apr. 11, 2001, pending entitled, “ConductiveCarbon Filled Polyvinyl Butyral Adhesive;” U.S. patent application Ser.No. 09/833,488 (D/A0895Q1), filed Apr. 11, 2001, pending entitled, “DualCuring Process for Producing A Puzzle Cut Seam;” U.S. patent applicationSer. No. 09/833,546 (A0584) filed Apr. 11, 2001, pending entitled“Imageable Seamed Belts Having Polyamide Adhesive Between InterlockingSeaming Members; and U.S. patent application Ser. No. 09/833,507(A0584Q) filed Apr. 11, 2001, pending entitled “Polyamide and ConductiveFiller Adhesive;” and U.S. Pat. No. 6,576,078 filed Apr. 11, 2001entitled “Flashless Hot Melt Bonding of Adhesives for Imageable SeamedBelts.” The disclosures of each of these references are herebyincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention is directed to an endless flexible seamed beltwherein an image can be transferred at the seam of the belt with littleor no print defects caused by the seam. In embodiments, the presentinvention relates to xerographic component imageable seamed beltscomprising an adhesive formed between interlocking elements of a seam.In an embodiment, an overcoat, and preferably a polyvinylbutyral andisocyanate overcoat, or a polyurethane overcoat from the reaction of apolyvinylbutyral and isocyanate, is positioned over the imageable seamedbelt. The present invention, in embodiments, provides a belt, which haslow surface energy and low friction. The present invention furtherprovides, in embodiments, a belt having a seam with increased strength.The present invention, in embodiments, also provides a belt in which anincrease in toner transfer efficiency and a decrease or elimination oftoner disturbance is possible, due to an improvement in controlledconductivity. The belt, in embodiments, further allows for improvedcleaning because of the increased toner transfer efficiency. Inembodiments, a cleanerless system is realized. The present inventionfurther provides, in embodiments, a reduced energy consumption due, inpart, to a decrease in necessary cure temperature. A broader latitude ofseam adhesives can be used with the outer layer, and the outer layer isfurther inexpensive as an overcoat. The coating, in embodiments, hasincreased adhesion to substrate materials. The belt, in embodiments,allows for image transfer at the seam, which cannot be accomplished withknown seamed belts.

In a typical electrostatographic reproducing apparatus such as anelectrophotographic imaging system using a photosensitive member, alight image of an original to be copied is recorded in the form of anelectrostatic latent image upon a photosensitive member and the latentimage is subsequently rendered visible by the application of a developermixture. One type of developer used in such printing machines is aliquid developer comprising a liquid carrier having toner particlesdispersed therein. Generally, the toner is made up of resin and asuitable colorant such as a dye or pigment. Conventional charge directorcompounds may also be present. The liquid developer material is broughtinto contact with the electrostatic latent image and the colored tonerparticles are deposited thereon in image configuration.

The developed toner image recorded on the imaging member is transferredto an image receiving substrate such as paper via a transfer member. Thetoner particles may be transferred by heat and/or pressure to a transfermember, or more commonly, the toner image particles may beelectrostatically transferred to the transfer member by means of anelectrical potential between the imaging member and the transfer member.After the toner has been transferred to the transfer member, it is thentransferred to the image receiving substrate, for example by contactingthe substrate with the toner image on the transfer member under heatand/or pressure.

Transfer members enable high throughput at modest process speeds. Infour-color photocopier or printer systems, the transfer member alsoimproves registration of the final color toner image. In such systems,the four component colors of cyan, yellow, magenta and black may besynchronously developed onto one or more imaging members and transferredin registration onto a transfer member at a transfer station.

In electrostatographic printing and photocopy machines in which thetoner image is transferred from the transfer member to the imagereceiving substrate, it is desired that the transfer of the tonerparticles from the transfer member to the image receiving substrate besubstantially 100 percent. Less than complete transfer to the imagereceiving substrate results in image degradation and low resolution.Complete transfer is particularly desirable when the imaging processinvolves generating full color images since undesirable colordeterioration in the final colors can occur when the color images arenot completely transferred from the transfer member.

Thus, it is desirable that the transfer member surface has excellentrelease characteristics with respect to the toner particles.Conventional materials known in the art for use as transfer membersoften possess the strength, conformability and electrical conductivitynecessary for use as transfer members, but can suffer from poor tonerrelease characteristics, especially with respect to higher gloss imagereceiving substrates.

Polyimide substrate transfer members are suitable for high performanceapplications because of their outstanding mechanical strength andthermal stability, in addition to their good resistance to a wide rangeof chemicals. However, the high cost of manufacturing unseamed polyimidebelts has led to the introduction of a seamed belt. Polyimides with thebest mechanical and chemical properties often exhibit poor adhesion atthe seam even when commercially available primers are used. Further,polyimide materials exhibit relatively high surface energy and highfriction, which decrease toner transfer efficiency in transfix andtransfuse applications. In order to have high toner transfer efficiency,higher electric fields are typically required to transfer the toner andvarious costly cleaning apparatuses are employed to remove residualtoner that does not transfer. In addition, present imageable seam beltsubstrates such as polyimides have high surface resistivity, whichreduces the electrical latitude of seam adhesives and causes tonerdisturbance. Meanwhile, the seam strength of imageable seams can berelatively low due to superfinishing of the seam area. These seams arefragile and may be easily damaged if mishandled.

Therefore, it is desired to provide a belt, which has the desiredproperties of the polyimide belt, but with low surface energy, lowfriction, and controlled conductivity. Such a belt will increase tonertransfer efficiency, improve cleaning and consequently reduce the energyconsumption. Further, it is desired to provide a belt, which hasincreased strength. Also, it is desirable to provide a belt, which workswell with a broader latitude of seam adhesives. Moreover, it isdesirable to provide a belt, which is relatively inexpensive. Inaddition, it is desirable to provide a seam, which is imageable, therebyreducing or eliminating the presence of print or copy defects.

U.S. Pat. No. 5,549,193 relates to an endless flexible seamed beltcomprising puzzle cut members, wherein at least one receptacle has asubstantial depth in a portion of the belt material at the belt ends.

U.S. Pat. No. 5,721,032 discloses a puzzle cut seamed belt having astrength-enhancing strip.

U.S. Pat. No. 5,487,707 discloses a puzzle cut seamed belt having a bondbetween adjacent surfaces, wherein an ultraviolet cured adhesive is usedto bond the adjacent surfaces.

U.S. Pat. No. 5,514,436 relates to a puzzle cut seamed belt having amechanically invisible seam, which is substantially equivalent inperformance to a seamless belt.

U.S. Pat. No. 5,525,446 describes an intermediate transfer memberincluding a base layer and top thermoplastic film forming polymer layer.The base layer can include a polycarbonate film, and the top layer caninclude polybutylenes. The belt can comprise an adhesive layer such as apolyvinylbutyral adhesive layer.

SUMMARY OF THE INVENTION

Embodiments of the present invention include: an endless seamed flexiblebelt comprising a first end and a second end, each of the first end andthe second end comprising a plurality of mutually mating elements whichjoin in an interlocking relationship to form a seam, the seam comprisingan adhesive, and the belt comprising a substrate and an outer layercomprising a polyurethane derived from a polyvinylbutyral andisocyanate.

In addition, embodiments of the present invention include: an endlessseamed flexible belt comprising a first end and a second end, each ofthe first end and the second end comprising a plurality of mutuallymating elements which join in an interlocking relationship to form aseam, the belt comprising a polyimide substrate and an outer layercomprising a polyurethene derived from a polyvinylbutyral crosslinkedwith a block isocyanate.

Embodiments further include: an image forming apparatus for formingimages on a recording medium comprising: a charge-retentive surface toreceive an electrostatic latent image thereon; a development componentto apply toner to the charge-retentive surface to develop theelectrostatic latent image to form a developed image on the chargeretentive surface; a transfer belt to transfer the developed image fromthe charge retentive surface to a copy substrate, wherein the transferbelt is an endless seamed flexible belt comprising a first end and asecond end, each of the first end and the second end comprising aplurality of mutually mating elements which join in an interlockingrelationship to form a seam, the transfer belt comprising a substrateand an outer layer comprising a polyurethane derived frompolyvinylbutyral and isocyanate; and a fixing component to fuse thedeveloped image to the copy substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference may behad to the accompanying figures.

FIG. 1 is a depiction of an electrostatographic apparatus.

FIG. 2 is an enlargement of a transfer system according to an embodimentof the present invention.

FIG. 3 is an enhanced view of an embodiment of a belt configuration andseam according to the present invention.

FIG. 4 is an enlargement of a puzzle cut seam having head and neckmembers according to one embodiment of the present invention.

FIG. 5 is an enlargement of a puzzle cut seam having mushroom-shapedpuzzle cut members according to another embodiment of the presentinvention.

FIG. 6 is an enlargement of a puzzle cut seam having dovetail membersaccording to another embodiment of the present invention.

FIG. 7 is an enlargement of a puzzle cut seam having recessor and teethmembers according to another embodiment of the present invention.

FIG. 8 is an enlargement of a puzzle cut seam having receptacle andprojection members of differing depth according to another embodiment ofthe present invention.

FIG. 9 is an enlarged version of a belt according to one embodiment ofthe present invention and demonstrates a crevice between the puzzle cutmembers, the crevice containing an adhesive.

FIG. 10 is an enlarged overhead view of a belt according to anembodiment of the invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention relates to an endless flexible seamed belt havinga puzzle cut seam, wherein the belt comprises an outer layer includingpolyvinylbutyral and isocyanate. The belt, in embodiments, has lowsurface energy and low friction. This results in an improvement incleaning, and possibly, enables a cleanerless system. The overcoat, inembodiments, improves the mechanical strength of the seamed belt bycovering up the interlocking members which can sometimes contain fragilepetals, and protecting them from the cleaning blade. The added thicknessof the overcoat layer, in embodiments, allow for an increase in pullstrength and flex life of the seamed area. Also, the belt, inembodiments, provides an increase in toner transfer efficiency and adecrease or elimination of toner disturbance, both due to theimprovement in controlled conductivity. The belt, in embodiments,further allows for reduced energy consumption due, in part, to theability to cure at a relatively low temperature. The low temperaturecure is less likely to cause physical distortion of the coatings. Thecoating, in embodiments, covers the seam with good topography. The belt,in embodiments, allows for image transfer at the seam, which cannot beaccomplished with known seamed belts. The conductivity-controlledovercoat, in embodiments, can hide image-distorting imperfections in thesubstrate material and particularly in the imageable seam area to enablewider latitude of substrate/adhesive choices. By broadening the latitudeof substrate and adhesive choices, in embodiments, a lower costimageable seam can be enabled.

In embodiments, the belt is an intermediate transfer belt, sheet,roller, or film useful in xerographic, including digital, apparatuses.However, the belts herein having an outer layer comprisingpolyvinylbutyral and isocyanate, can be useful as belts, rollers, drelts(cross between drum and belt), and the like, for many differentprocesses and components such as photoreceptors, fusing members,transfix members, bias transfer members, bias charging members,developer members, image bearing members, conveyor members, cleaningmembers, and other members for contact electrostatic printingapplications, xerographic applications, including digital, and the like.Further, the belts, herein, can be used for both liquid and powderxerographic architectures.

Referring to FIG. 1, in a typical electrostatographic reproducingapparatus, a light image of an original to be copied is recorded in theform of an electrostatic latent image upon a photosensitive member andthe latent image is subsequently rendered visible by the application ofelectroscopic thermoplastic resin particles which are commonly referredto as toner. Specifically, photoreceptor 10 is charged on its surface bymeans of a charger 12 to which a voltage has been supplied from powersupply 11. The photoreceptor is then image wise exposed to light from anoptical system or an image input apparatus 13, such as a laser and lightemitting diode, to form an electrostatic latent image thereon.Generally, the electrostatic latent image is developed by bringing adeveloper mixture from developer station 14 into contact therewith.Development can be effected by use of a magnetic brush, powder cloud, orother known development process.

After the toner particles have been deposited on the photoconductivesurface, in image configuration, they are transferred to a copy sheet 16by transfer means 15, which can be pressure transfer or electrostatictransfer. Preferably, the developed image can be transferred to anintermediate transfer member and subsequently transferred to a copysheet.

After the transfer of the developed image is completed, copy sheet 16advances to fusing station 19, depicted in FIG. 1 as fusing and pressurerolls, wherein the developed image is fused to copy sheet 16 by passingcopy sheet 16 between the fusing member 20 and pressure member 21,thereby forming a permanent image. Fusing may be accomplished by otherfusing members such as a fusing belt in pressure contact with a pressureroller, fusing roller in contact with a pressure belt, or other likesystems. Photoreceptor 10, subsequent to transfer, advances to cleaningstation 17, wherein any toner left on photoreceptor 10 is cleanedtherefrom by use of a blade 22 (as shown in FIG. 1), brush, or othercleaning apparatus.

FIG. 2 is a schematic view of an image development system containing anintermediate transfer member. FIG. 2 demonstrates another embodiment ofthe present invention and depicts a transfer apparatus 15 comprising atransfer member 1 positioned between an imaging member 10 and a transferroller 6. The imaging member 10 is exemplified by a photoreceptor drum.However, other appropriate imaging members may include otherelectrostatographic imaging receptors such as ionographic belts anddrums, electrophotographic belts, and the like.

In the multi-imaging system of FIG. 2, each image being transferred isformed on the imaging drum by image forming station 12. Each of theseimages is then developed at developing station 13 and transferred totransfer member 2. Each of the images may be formed on the photoreceptordrum 10 and developed sequentially and then transferred to the transfermember 2. In an alternative method, each image may be formed on thephotoreceptor drum 10, developed, and transferred in registration to thetransfer member 2. In a preferred embodiment of the invention, themulti-image system is a color copying system. In this color copyingsystem, each color of an image being copied is formed on thephotoreceptor drum. Each color image is developed and transferred to thetransfer member 2. As above, each of the colored images may be formed onthe drum 10 and developed sequentially and then transferred to thetransfer member 2. In the alternative method, each color of an image maybe formed on the photoreceptor drum 10, developed, and transferred inregistration to the transfer member 2.

After latent image forming station 12 has formed the latent image on thephotoreceptor drum 10 and the latent image of the photoreceptor has beendeveloped at developing station 13, the charged toner particles 4 fromthe developing station 13 are attracted and held by the photoreceptordrum 10 because the photoreceptor drum 10 possesses a charge 5 oppositeto that of the toner particles 4. In FIG. 2, the toner particles areshown as negatively charged and the photoreceptor drum 10 is shown aspositively charged. These charges can be reversed, depending on thenature of the toner and the machinery being used. In a preferredembodiment, the toner is present in a liquid developer. However, thepresent invention, in embodiments, is useful for dry development systemsalso.

A biased transfer roller 6 positioned opposite the photoreceptor drum 10has a higher voltage than the surface of the photoreceptor drum 10. Asshown in FIG. 2, biased transfer roller 6 charges the backside 7 oftransfer member 2 with a positive charge. In an alternative embodimentof the invention, a corona or any other charging mechanism may be usedto charge the backside 7 of the transfer member 2.

The negatively charged toner particles 4 are attracted to the front side8 of the transfer member 2 by the positive charge 9 on the backside 7 ofthe transfer member 2.

FIG. 3 demonstrates an example of an embodiment of a belt in accordancewith the present invention. Belt 30 is demonstrated with seam 31. Seam31 is pictured as an example of one embodiment of a puzzle cut seam. Thebelt is held in position and turned by use of rollers 32. Note that themechanical interlocking relationship of the seam 31 is present in atwo-dimensional plane when the belt 30 is on a flat surface, whether itbe horizontal or vertical. While the seam is illustrated in FIG. 3 asbeing perpendicular to the two parallel sides of the belt, it should beunderstood that it may be angled or slanted with respect to the parallelsides. This enables any noise generated in the system to be distributedmore uniformly and the forces placed on each mating element or node tobe reduced.

The seam formed according to the present invention is one having a thinand smooth profile, of enhanced strength, improved flexibility andextended mechanical life. In an embodiment, the belt ends can be heldtogether by the geometric relationship between the ends of the beltmaterial, which are fastened together by a puzzle cut. Alternatively,overlapping, interlocking seam members can be present. The puzzle cutseam can be of many different configurations, but is one in which thetwo ends of the seam interlock with one another in a manner of a puzzle.Specifically, in embodiments, the mutually mating elements comprise afirst projection and a second receptacle geometrically oriented so thatthe second receptacle on the first end receives the first projection onthe second end and wherein the first projection on the first end isreceived by the second receptacle on the second end. The seam has akerf, void or crevice between the mutually mating elements at the twojoining ends of the belt, and that crevice can be filled with anadhesive according to the present invention. The opposite surfaces ofthe puzzle cut pattern are bound or joined together to enable the seamedflexible belt to essentially function as an endless belt. The belt, inembodiments, provides improved seam quality and smoothness withsubstantially no thickness differential between the seam and theadjacent portions of the belt.

An example of an embodiment of a puzzle cut seam having two ends, eachof the ends comprising puzzle cut members or mutually mating elements isshown in FIG. 4. The puzzle cut pattern may take virtually any form,including that of nodes such as identical post or neck 34 and head 33 ornode patterns having projections 36 and receptacles 35 which interlockwhen brought together as illustrated in FIG. 4. The puzzle cut patternmay also be of a more mushroom-like shaped pattern having firstprojections 38 and 39 and second receptacles 40 and 37 as illustrated inFIG. 5, as well as a dovetail pattern as illustrated in FIG. 5 havingfirst projections 41 and second receptacles 42. The puzzle cut patternillustrated in FIG. 7 has a plurality of first fingers 43 withinterlocking teeth 44 and plurality of second fingers 45 which haverecesses 46 to interlock with the teeth 44 when assembled. It ispreferred that the interlocking elements all have curved mating elementsto reduce the stress concentration between the interlocking elements andpermit them to separate when traveling around curved members such as therolls 32 of FIG. 3. It has been found that with curved mating elementsthat the stress concentration is lower than with square corners whererather than the stress being uniformly distributed it is concentratedleading to possible failure.

Another example of a puzzle cut seam is shown in FIG. 8 in which themutually mating elements or puzzle cut members comprise a first member50 and a second member 51, wherein the first member 50 comprises a firstreceptacle 52 and a first projection 54, and the second member 51comprises a second receptacle 55 and a second projection 56. The firstreceptacle 52 of the first member 50 receives the second projection 56of the second member 51, and the second receptacle 55 of the secondmember 51 receives the first projection 54 of the first member 50. Inorder to reduce the height differential between the seamed portion andthe adjacent, unseamed portion of the belt, it is desirable to have thesecond receptacles formed within their individual members at asubstantial depth in a portion of the belt as the belt ends.

In embodiments, the height differential between the seam and the rest ofthe belt (the nonseamed portions of the belt) is practically nil, orfrom about 0 to about 25 micrometers, preferably from about 0.0001 toabout 25 micrometers, and particularly preferred of from about 0.01 toabout 5 micrometers. It is also preferred that any height differencebetween the seam and substrate be tapered and not abrupt.

The outer layer comprises polyvinylbutyral and an isocyanate, orpolyurethane prepared by the reaction of polyvinylbutyral and anisocyanate. Examples of polyvinylbutyrals include a copolymer, whichcontains polyvinyl alcohol, acetate and a butyral segment. Commerciallyavailable examples of polyvinylbuyral include BUTVAR® B90, B76, B79 andB98 from Solutia.

In embodiments, the polyvinylbutyral can be blended with other polymers.Examples of suitable polymers to be blended with polyvinylbutyralinclude phenolic, melamine, rosin derivatives, polyester, acrylic,isocyanates, alkyd, PTFE (polytetrafluoroethylene) powder, silicone,functional siloxane, fluorocarbons, and the like. In embodiments whereinthe polymer is an isocyanate, the isocyanate can be a block isocyanate.In embodiments, the isocyanate can be selected from the group consistingof aliphatic and aromatic based isocyanates or their prepolymers.Commercially available isocyanates include block isocyanate BL3175 andBL 4265 from Bayer.

In optional embodiments, the outer layer can further comprise othercurative polymers such as phenolic polymers, epoxies, dialdehydes andmelamines, and the like, and mixtures thereof.

A surface resistivity range for toner transfer performance can be fromabout 10² to about 10¹⁵ ohm/sq, or from about 10⁶ to about 10¹⁴ ohm/sq.A volume resistivity for toner transfer performance can be from about10⁸ to about 10¹¹ ohm-cm. When the belt and the seam of the belt havethe same or substantially the same electrical resistance, toner transferat the seam is the same or substantially the same as the transfer at thebelt. Such transfer at the seam provides an invisible or substantiallyinvisible seam.

The overcoated belt has excellent properties including low surfaceenergy, mechanical strength, desired resistivity and thermal stability.The belt has a sliding coefficient against paper of from about 0.1 toabout 0.4, or from about 0.18 to about 0.28. If the overcoat comprisesfillers, the coefficient of friction is from about 0.3 to about 0.4, andan unfilled coating will have a coefficient of friction of from about0.18 to about 0.28. The coefficient of friction against paper for anun-coated polyimide (KAPTON®) film, can be from about 0.3 to about 0.5.

The coated belt has a decrease surface energy. For example, the coatedbelt has a surface energy of from about 10 to about 40, or from about 20to about 30, or 24 dyn/cm. The coating without fillers can have asurface energy of about 24 dyn/cm. The surface energy of un-coatedpolyimide (KAPTON®) film is about 43 dyn/cm.

The electrical properties of the belt seam, or layers of the belt, canbe controlled by varying the amount of fillers, by changing the type offiller added, and/or by changing the curing procedure.

Fillers can be added to the substrate and/or to the adhesive and/or tothe outer layer so as to impart desired electrical resistivity. Examplesof suitable fillers for use in the substrate, adhesive and/or outerlayer include carbon fillers, metal oxide fillers, doped metal oxidefillers, other metal fillers, polymer fillers, other conductive fillers,and the like. Specific examples of fillers include carbon fillers suchas carbon black, fluorinated carbon black, graphite, low conductivecarbon, and the like, and mixtures thereof; metal oxides such as indiumtin oxide, zinc oxide, iron oxide, aluminum oxide, copper oxide, leadoxide, and the like, and mixtures thereof; doped metal oxides such asantimony-doped tin oxide, antimony-doped titanium dioxide,aluminum-doped zinc oxide, similar doped metal oxides, and mixturesthereof; polymer fillers such as polyaniline, polythiophenes [forexample, polythiophene sulfone (BAYTRON®)], polypyrrole,polydimethylsiloxane, polytetrafluoroethylene, and the like, andmixtures thereof; ionic conductors such as alkali alkyl sulfonates,quaternary ammonium salts, phosphonium salts, doped polyaniline, and thelike, and mixtures thereof; Examples of commercially available fillersinclude fluorinated carbon (such as ACCUFLUOR® from Allied Signal ofMorristown, N.J.), ZELEC® (antimony doped tin oxide) available fromDuPont, Wilmington, Del., BAYTRON® P and BAYTRON® M (polymer whichcontain poly-ethylendioxythiophene), BAYTRON® being a trademark of BayerCorporation, Pittsburgh, Pa.

One type of fluorinated carbon includes those having the formula CF_(x)with x representing the number of fluorine atoms and generally being upto about 1.5, preferably from about 0.01 to about 1.5, and particularlypreferred from about 0.04 to about 1.4. Other preferred fluorinatedcarbons are poly(dicarbon monofluoride) which is usually written in theshorthand manner (C₂F)_(n). Preferred fluorinated carbons selectedinclude those described in U.S. Pat. No. 4,524,119 to Luly et al., thesubject matter of which is hereby incorporated by reference in itsentirety, and those having the tradename ACCUFLUOR®, (ACCUFLUOR® is a isregistered trademark of Allied Signal, Morristown, N.J.) for example,ACCUFLUOR® 2028, ACCUFLUOR® 2065, ACCUFLUOR® 1000, and ACCUFLUOR® 2010.ACCUFLUOR® 2028 and ACCUFLUOR® 2010 have 28 and 11 percent by weightfluorine, respectively, based on the weight of fluorinated carbon.ACCUFLUOR® 1000 and ACCUFLUOR® 2065 have 62 and 65 percent by weightfluorine, respectively, based on the weight of fluorinated carbon. Also,ACCUFLUOR® 1000 comprises carbon coke, whereas ACCUFLUOR® 2065, 2028 and2010 all comprise conductive carbon black. These fluorinated carbons areof the formula CF_(x) and are formed by the reaction of C+F₂=CF_(x).

The filler, if present in the substrate, can be present in an amount offrom about 1 to about 60, or from about 3 to about 40 percent by weightof total solids. Total solids, as used herein, refers to the amount ofsolids present in the substrate, layer, or adhesive. The filler, ifpresent in the adhesive, can be present in an amount of from about 2 toabout 60, or from about 5 to about 30 percent by weight of total solids.The filler, if present in the outer layer, can be present in an amountof from about 6 to about 10 percent by weight of total solids.

An example of a preferred belt used is depicted in FIG. 10. The belt 30comprises a substrate 60, having therein, in embodiments, conductivefillers 61. The belt contains seam 31 having an adhesive 63 positionedbetween the seam members 64 and 65. In an embodiment, conductive fillers62 are dispersed or contained in the adhesive. In an embodiment of theinvention, the polyvinybutyral and isocyanate, or the polyurethane fromthe reaction of polyvinybutyral and isocyanate, overcoat 66 is providedover the substrate 60. The overcoat may contain conductive fillers 67.Conductive fillers 61 optionally dispersed or contained in thesubstrate, fillers 67 optionally dispersed or contained in the overcoat,and fillers 62 optionally contained or dispersed in the adhesive, may bethe same or different.

Examples of suitable substrate materials include semiconductivepolyimides such as polyaniline-filled polyimide, carbon-filledpolyimides, antimony doped tin oxide-filled polyimide, carbon-filledpolycarbonate, and the like. Examples of commercially availablepolyimide substrates include KAPTON® and UPLIEX® both from DuPont, andULTEM® from GE.

An adhesive is preferably present between the seam, and placed in thecrevice between the puzzle cut members to a thickness of from about0.0001 to about 50 micrometers. As shown in one embodiment of a puzzlecut seam 31 according to the present invention, the adhesive is presentbetween the puzzle cut members and at the seam crevice 57 of FIG. 9.

Because of the chemistry of the outer layer of the belt, a variety ofadhesives can be used. The outer layer is compatible with many types ofadhesives. Examples of suitable adhesives include fluoropolymeradhesives such as fluorinated urethanes (for example, fluoroethylenevinyl ether based polyurethanes, fluorinated epoxy polyurethane,fluorinated acrylic polyurethanes, and the like, and polymers thereofand mixtures thereof); polyvinylbutyral adhesives, epoxy adhesives,polyimide adhesives, polyurethane adhesives, polyamide adhesives such asDHTBD filled LUCKAMIDE® and other high temperature adhesives such aspolyaniline filled polyimide, nitrile phenolic, and the like.

The belt may be prepared by adding an adhesive solution between thesubstrate interlocking members by any suitable means such as using acotton tipped applicator, liquid dispenser, glue gun and other knownmeans. The adhesive is placed between seaming members and the seamingmembers are brought together and bonded using known methods, and othermethods such as that described in U.S. Pat. No. 6,576,078, filed Apr.11, 2001, entitled, “Flashless Hot Melt Bonding of Adhesives forImageable Seamed Belts.” The disclosure of this reference is herebyincorporated by reference herein in its entirety.

The outer layer is prepared by mixing the polyvinylbutyral with theisocyanate in the presence of a catalyst. Examples of suitable catalystsinclude tin catalyst, for example, dibutyl tin dilaurate (DBTDL). Thesolution is mixed for example, on a roll mill, and then coated on thesubstrate.

The outer layer may then be applied to the seamed substrate using avariety of common coating processes such as roll coating, gap coating,spray coating, dip coating, flow coating, and the like.

The outer layer is allowed to dry and then is postcured. The thermalcuring induces the crosslinking reaction of the polyvinylbutyral andisocyanate, and also activates the controlled conductivity mechanism inthe layers. Polyurethane is thereby formed. Curing procedures useful incuring the outer layer include thermal curing and infrared curing.Examples of heat curing include use of moderate heat once the adhesiveis placed in the seam crevice. This moderate heating also increases thecrosslinking/solidification reaction and increases the seam processingand belt fabrication speed. The relatively low temperature postcure isless likely to cause physical distortion of the seam and should coverthe seam with good topography. Desired temperature includes from about40 to about 200° C., preferably from about 120 to about 150° C., at atime of from about 30 seconds to about 24 hours, or from about 15minutes to about 3 hours, or from about 30 minutes to about 1 hour. Heatmay be applied by, for example, a heat gun, oven, or other suitablemeans.

All the patents and applications referred to herein are herebyspecifically, and totally incorporated herein by reference in theirentirety in the instant specification.

The following Examples further define and describe embodiments of thepresent invention. Unless otherwise indicated, all parts and percentagesare by weight.

EXAMPLES Example 1

Preparation of Intermediate Transfer Belt

A polyimide film substrate was obtained from DuPont. The belt substratewas comprised of polyaniline and carbon-filled polyimide. Theresistivity was tested and found to be from about 10¹² to about 10¹³ohm-cm. The belt ends that were to be joined were treated with a primershortly before assembly, to help improve adhesion. The puzzle cut endswere wiped with a 10% solution of 3-aminopropyltriethoxysilane (Aldrich)in toluene, and allowed to dry for about 10 minutes at 40° C.

Optionally, the belt ends to be joined can be subjected to a “chemicaletch” treatment to help improve adhesion. The puzzle cut ends can bedipped in 1N aqueous NaOH solution for about 10 minutes, followed by 10minutes in 1N aqueous HCl solution. The ends can then be rinsed withdistilled water and allowed to dry.

Example 2

Preparation of LUCKAMIDE® (Polyamide) and DHTBD Adhesive

An amount of about 100 grams LUCKAMIDE® was added to a mixture of 150grams methanol and 150 grams 1-propanol in a 1000-ml bottle. The bottlewas warmed to about 60° C. until the resin completely dissolved. To thewarm LUCKAMIDE® solution was added 60 grams DHTBD and the solution wasmixed well until all the solid dissolved. To this solution was thenadded 4.2 grams of oxalic acid dissolved in a minimal amount of methanoland also 14 grams of BLACK PEARLS® 2000 (carbon black) dispersion. Themixture was placed on a roll mill for about 1 hour to ensure completemixing.

The resulting dispersion was drawcoated onto a sheet of TEDLAR®. Asuitable sized coating bar was used. The coating was allowed to dry in adrying oven set at about 40° C. for about 3 hours. Once the film wasdry, it was kept on the release liner and was ready for use as a seamadhesive. The prepared adhesive tape was stored at below 0° C. tomaintain shelf life.

The stock dispersion of carbon black was prepared earlier by attriting10 grams of BLACK PEARLS® 2000 along with 10 grams LUCKAMIDE® dispersedin 150 grams 1-propanol for about 3 hours, using a bench top attritorcharged with {fraction (3/16)}″ stainless steel shot media. The slurrywas filtered through a course screen to separate out the media and thecarbon dispersion was collected in an 8 ounce polyethylene bottle.

Example 3

Preparation of Puzzle Cut Seamed Belt

The two puzzle cut ends of the polyimide film prepared in Example 1 werebrought together and aligned on the lower jaw of a Technoseal VertrodThermal Impulse Heat Sealer (Mod. 20EP/P-1/4-WC-CAN-DIG-I) with theassistance of vacuum holdown tables mounted on both sides of a welder. Afreestanding film of the adhesives/release layer (preferably about 8 toabout 80 microns thick) formed in accordance with any of the examplesabove were selected. A narrow strip (about 1 to about 4 cm wide) ofmaterial was cut to a length and width sufficient to adequately coverthe puzzle-cut seam area on the belt substrate. The strip ofadhesive/release layer was laid across the top of the seam area coveringthe seam. The welder was set to a nominal impulse temperature of about120° C., equivalent to the crosslinking temperature of the LUCKAMIDE®.The seam was welded with applied temperature and pressure for about 10minutes to compression mold the adhesive into the seam kerf, filling itcompletely. This also initiated crosslinking of the adhesive. Postcuring at 120° C. for an additional 30 minutes was required to furthercrosslink and improve the mechanical properties of the adhesive.

Other methods of hot melt adhesive bonding can be used as well. Forexample, a heated roll or heated shoe that can move along the seam canbe used. The seamed belt was removed from the fixture, post cured, andthe seam was subjected to finishing (sanding) and polishing steps toremove excess adhesive and bring the seam area topography in line withthe rest of the belt.

Example 4

Preparation of Non-Filled Polyvinylbutyral and Isocyanate CoatingSolution

An amount of 4.6 grams BUTVAR® 79 was dissolved in 15.4 grams solvent (a2:1 mixture of methyl ethyl ketone and ethyl acetate) in a 50-ml bottle.To this solution was added 13.4 grams BL3175 and 0.07 grams FASCAT®4200. The solution was mixed on a roll mill for about 30 minutes. Thecompleted solution was then coated on the polyimide substrate preparedin accordance with Example 1. The belt was cured in a forced air oven at150° C. for about 30 minutes.

Example 5

Preparation of Filled Polyvinylbutyral and Isocyanate Outer Layer

An amount of about 0.066 grams (1 pph) of fluorinated carbon (ACCUFLUOR®2010 from Allied Chemical) (Sample 1) and 0.198 grams (3 pph) offluorinated carbon (ACCUFLUOR® 2028 from Allied Chemical) (Sample 2) waseach separately suspended in about 5 grams methyl ethyl ketone in a 50ml bottle. The mixtures were each agitated in an ultrasonic bath forabout 15 minutes to disperse the carbon particles. To the dispersionswere added 0.26 grams (4 pph) DIAK 3 (from Dupont) and mixed well.Subsequently, about 15 grams of polyvinylbutyral/urethane solutionprepared in Example 4 were added separately to each sample. Theresulting solutions were mixed on a roll mill for about 1 hour. Theresultant dispersions were each drawcoated onto the polyimide substrateformed in Example 1.

The coatings were allowed to dry well and then were postcured in an ovenfor about 30 minutes at 150° C. The thermal treatment served twofunctions. First, it induced the crosslinking reaction and second, italso activated the controlled conductivity mechanism in the layers.

Example 6

Testing of the Filled Polyvinylbutyral and Isocyanate Outer Layer

Several samples of filled polyvinylbutyral and isocyanate layersprepared in accordance with Example 3 were subjected to testing ofresistivity. The filler loadings were varied in the different samples.The resistivity of the samples had been tested by an in-house surfaceresistive meter and Trek PO661 resistive test fixture (from Trek Inc.).Table 1 below shows the results of the testing.

TABLE 1 Sample Number Accufluor ® 2010 Accufluor ® 2028 Resistivity 11.0 3.0 1.6 × 10¹³ 2 1.5 3.0 7.8 × 10¹¹ 3 2.0 3.0 1.6 × 10¹¹ 4 2.5 3.06.8 × 10¹⁰ 5 3.0 3.0 6.9 × 10⁹

The outer layer was shown to have excellent adhesion to the substratebased on the crosshatch adhesion test. The surfaces of the outer layersdemonstrated a low coefficient of friction (COF) and low surface energy.The COF to paper and KAPTON® (polyimide) was in the range of from about0.18 to about 0.28, and the surface energy was about 24 dyn/cm, Tonertransfer efficiency was about 99% better than polyimide, which showed97% toner transfer. The surface conductivity of the outer layer can betuned to from about 10⁶ to about 10¹⁴ ohm/cm by changing the conductivefiller loading. The pull force of the overcoated seamed belt increasedto from 10 to about 30% from a 15 to 20 lb/inch range, to from about 25to about 30 lb/inch range.

While the invention has been described in detail with reference tospecific and preferred embodiments, it will be appreciated that variousmodifications and variations will be apparent to the artisan. All suchmodifications and embodiments as may readily occur to one skilled in theart are intended to be within the scope of the appended claims.

We claim:
 1. An image forming apparatus for forming images on arecording medium comprising: a charge-retentive surface to receive anelectrostatic latent image thereon; a development component to applytoner to said charge-retentive surface to develop said electrostaticlatent image to form a developed image on said charge retentive surface;a transfer belt to transfer the developed image from said chargeretentive surface to a-copy substrate, wherein said transfer belt is anendless seamed flexible belt comprising a first end and a second end,each of said first end and said second end comprising a plurality ofmutually mating elements which join in an interlocking relationship toform a seam, said transfer belt comprising a substrate and an outerlayer comprising a polyurethane derived from polyvinylbutyral andisocyanate; and a fixing component to fuse said developed image to saidcopy substrate.
 2. An image forming apparatus in accordance with claim1, wherein said substrate comprises a polyimide.
 3. An image formingapparatus in accordance with claim 1, wherein said outer layer furthercomprises a fluorocarbon.
 4. An image forming apparatus in accordancewith claim 1, wherein said isocyanate is a block isocyanate.
 5. An imageforming apparatus in accordance with claim 1, wherein said outer layercomprises an electrically conductive filler.
 6. An image formingapparatus in accordance with claim 5, wherein said electricallyconductive filler is selected from the group consisting of carbonfiller, metal filler, metal oxide filler, doped metal oxide filler,ionic conductive filler, polymer fillers, and mixtures thereof.
 7. Animage forming apparatus in accordance with claim 6, wherein said carbonfiller is selected from the group consisting of carbon, graphite,fluorinated carbon, and mixtures thereof.
 8. An image forming apparatusin accordance with claim 6, wherein said doped metal oxide is antimonydoped tin oxide.
 9. An image forming apparatus in accordance with claim6, wherein said ionic conductor is selected from the group consisting ofalkali alkyl sulfonates, quaternary ammonium salts, phosphonium salts,and mixtures thereof.
 10. An image forming apparatus in accordance withclaim 6, wherein said polymer filler is selected from the groupconsisting of polyanilines, polythiophenes, polypyrrolles, and mixturesthereof.
 11. An image forming apparatus in accordance with claim 6,herein said electrically conductive filler comprises doped polyaniline,antimony doped tin oxide and carbon black.
 12. An image formingapparatus in accordance with claim 1, wherein said seam comprises anadhesive comprising a material selected from the group consisting ofpolyvinyl butyral, nitrile phenolic, epoxy, polyimide, polyurethane,polyamide, and mixtures thereof.
 13. An image forming apparatus inaccordance with claim 1, wherein said outer layer has a surface energyof from about 10 to about 40 dyn/cm to water.
 14. An image formingapparatus in accordance with claim 1, wherein said outer layer has asliding coefficient of from about 0.1 to about 0.4.
 15. An image formingapparatus in accordance with claim 1, wherein said belt has a surfaceresistivity of from about 10² to about 10¹⁵ ohm/sq.
 16. An image formingapparatus in accordance with claim 1, wherein said belt has a surfaceresistivity of from about 10⁶ to about 10⁴ ohm/sq.
 17. An image formingapparatus in accordance with claim 1, wherein said belt is anintermediate transfer belt.
 18. An image forming apparatus in accordancewith claim 1, wherein said plurality of mutually mating elements are inthe form of a puzzle cut pattern.